An organization of workers that negotiates with employers to maintain or improve wages, benefits and working conditions. A union represents workers in a particular industry, such as teachers in a local school district. In the United States, unions have the legal right, under the National Labor Relations Act, to negotiate collectively with employers over the terms and conditions of their workers’ employment. Both sides must agree on these terms. This is called “collective bargaining.” In some circumstances, workers feel their rights are being violated and may threaten strikes (mass refusal by the workers to perform their work) or other collective action through their union to try to force employers to agree to what they want. Similarly, employers can close the workplaces and hire new workers to force the unions to agree to their terms.